Maternal obesity increases the risk for pediatric obesity; however, the molecular mechanisms in human infants remain poorly understood. We hypothesized that mesenchymal stem cells (MSCs) from infants born to obese mothers would demonstrate greater potential for adipogenesis and less potential for myogenesis, driven by differences in β-catenin, a regulator of MSC commitment. MSCs were cultured from the umbilical cords of infants born to normal-weight (prepregnancy [pp] BMI 21.1 ± 0.3 kg/m(2); n = 15; NW-MSCs) and obese mothers (ppBMI 34.6 ± 1.0 kg/m(2); n = 14; Ob-MSCs). Upon differentiation, Ob-MSCs exhibit evidence of greater adipogenesis (+30% Oil Red O stain [ORO], +50% peroxisome proliferator-activated receptor (PPAR)-γ protein; P < 0.05) compared with NW-MSCs. In undifferentiated cells, total β-catenin protein content was 10% lower and phosphorylated Thr41Ser45/total β-catenin was 25% higher (P < 0.05) in Ob-MSCs versus NW-MSCs (P < 0.05). Coupled with 25% lower inhibitory phosphorylation of GSK-3β in Ob-MSCs (P < 0.05), these data suggest greater β-catenin degradation in Ob-MSCs. Lithium chloride inhibition of GSK-3β increased nuclear β-catenin content and normalized nuclear PPAR-γ in Ob-MSCs. Last, ORO in adipogenic differentiating cells was positively correlated with the percent fat mass in infants (r = 0.475; P < 0.05). These results suggest that altered GSK-3β/β-catenin signaling in MSCs of infants exposed to maternal obesity may have important consequences for MSC lineage commitment, fetal fat accrual, and offspring obesity risk.

Gluconeogenesis is a complex metabolic process that involves multiple enzymatic steps regulated by myriad factors, including substrate concentrations, the redox state, activation and inhibition of specific enzyme steps, and hormonal modulation. At present, the most widely accepted technique to determine gluconeogenesis is by measuring the incorporation of deuterium from the body water pool into newly formed glucose. However, several techniques using radioactive and stable-labeled isotopes have been used to quantitate the contribution and regulation of gluconeogenesis in humans. Each method has its advantages, methodological assumptions, and set of propagated errors. In this review, we examine the strengths and weaknesses of the most commonly used stable isotopes methods to measure gluconeogenesis in vivo. We discuss the advantages and limitations of each method and summarize the applicability of these measurements in understanding normal and pathophysiological conditions.

The hypothesis that plasma prekallikrein (PK) is a risk factor for the development of vascular complications was assessed in a study using the Diabetes Control and Complications Trial (DCCT)/Epidemiology and Diabetes Interventions and Complications (EDIC) cohort of subjects with type 1 diabetes. The circulating levels of plasma PK activity were measured in the plasma of 636 subjects with type 1 diabetes (EDIC years 3-5). Common and internal carotid intima-media thickness (IMT) were measured by B-mode ultrasonography in EDIC years 1 and 6. Plasma PK levels were positively and significantly associated with BMI, hemoglobin A1c, systolic blood pressure, total cholesterol, LDL cholesterol, and triglycerides but not with age, sex, duration of diabetes, or HDL cholesterol. Univariate and multivariable statistical models after controlling for other risk factors consistently demonstrated a positive association between plasma PK and progression of internal carotid IMT. Multivariate analysis using a general linear model showed plasma PK to be significantly associated with progression of both internal and combined IMT (Wilks Λ P value of 0.005). In addition, the mean internal carotid IMT levels were higher in subjects with plasma PK levels in the highest 10th percentile compared with subjects with plasma PK levels in the lower 10th percentile (P = 0.048). These novel findings implicate plasma PK as a risk factor for vascular disease in type 1 diabetes.

Pancreatic β-cells modulate insulin secretion through rapid sensing of blood glucose and integration of gut-derived signals. Increased insulin demand during pregnancy and obesity alters islet function and mass and leads to gestational diabetes mellitus and type 2 diabetes in predisposed individuals. However, it is unclear how blood-borne factors dynamically access the islets of Langerhans. Thus, understanding the changes in circulating molecule distribution that accompany compensatory β-cell expansion may be key to developing novel antidiabetic therapies. Here, using two-photon microscopy in vivo in mice, we demonstrate that islets are almost instantly exposed to peaks of circulating molecules, which rapidly pervade the tissue before clearance. In addition, both gestation and short-term high-fat-diet feeding decrease molecule extravasation and uptake rates in vivo in islets, independently of β-cell expansion or islet blood flow velocity. Together, these data support a role for islet vascular permeability in shaping β-cell adaptive responses to metabolic demand by modulating the access and sensing of circulating molecules.

Clinical islet transplantation has become an established treatment modality for selected patients with type 1 diabetes. However, a large proportion of transplanted islets is lost through multiple factors, including immunosuppressant-related toxicity, often requiring more than one donor to achieve insulin independence. On the basis of the cytoprotective capabilities of antifreeze proteins (AFPs), we hypothesized that supplementation of islets with synthetic AFP analog antiaging glycopeptide (AAGP) would enhance posttransplant engraftment and function and protect against tacrolimus (Tac) toxicity. In vitro and in vivo islet Tac exposure elicited significant but reversible reduction in insulin secretion in both mouse and human islets. Supplementation with AAGP resulted in improvement of islet survival (Tac(+) vs. Tac+AAGP, 31.5% vs. 67.6%, P < 0.01) coupled with better insulin secretion (area under the curve: Tac(+) vs. Tac+AAGP, 7.3 vs. 129.2 mmol/L/60 min, P < 0.001). The addition of AAGP reduced oxidative stress, enhanced insulin exocytosis, improved apoptosis, and improved engraftment in mice by decreasing expression of interleukin (IL)-1β, IL-6, keratinocyte chemokine, and tumor necrosis factor-α. Finally, transplant efficacy was superior in the Tac+AAGP group and was similar to islets not exposed to Tac, despite receiving continuous treatment for a limited time. Thus, supplementation with AAGP during culture improves islet potency and attenuates long-term Tac-induced graft dysfunction.

Descriptions of insulitis in human islets throughout the natural history of type 1 diabetes are limited. We determined insulitis frequency (the percent of islets displaying insulitis to total islets), infiltrating leukocyte subtypes, and β-cell and α-cell mass in pancreata recovered from organ donors with type 1 diabetes (n = 80), as well as from donors without diabetes, both with islet autoantibodies (AAb(+), n = 18) and without islet autoantibodies (AAb(-), n = 61). Insulitis was observed in four of four donors (100%) with type 1 diabetes duration of ≤1 year and two AAb(+) donors (2 of 18 donors, 11%). Insulitis frequency showed a significant but limited inverse correlation with diabetes duration (r = -0.58, P = 0.01) but not with age at disease onset. Residual β-cells were observed in all type 1 diabetes donors with insulitis, while β-cell area and mass were significantly higher in type 1 diabetes donors with insulitis compared with those without insulitis. Insulitis affected 33% of insulin(+) islets compared with 2% of insulin(-) islets in donors with type 1 diabetes. A significant correlation was observed between insulitis frequency and CD45(+), CD3(+), CD4(+), CD8(+), and CD20(+) cell numbers within the insulitis (r = 0.53-0.73, P = 0.004-0.04), but not CD68(+) or CD11c(+) cells. The presence of β-cells as well as insulitis several years after diagnosis in children and young adults suggests that the chronicity of islet autoimmunity extends well into the postdiagnosis period. This information should aid considerations of therapeutic strategies seeking type 1 diabetes prevention and reversal.

Although numerous functions of extracellular signal-regulated kinase 1/2 (ERK1/2) are identified, a direct effect of ERK1/2 on liver steatosis has not been reported. Here, we show that ERK1/2 activity is compromised in livers of leptin receptor-deficient (db/db) mice. Adenovirus-mediated activation of mitogen-activated protein kinase kinase 1 (MEK1), the upstream regulator of ERK1/2, significantly ameliorated liver steatosis in db/db mice, increased expression of genes related to fatty acid β-oxidation and triglyceride (TG) export and increased serum β-hydroxybutyrate (3-HB) levels. Opposite effects were observed in adenovirus-mediated ERK1/2 knockdown C57/B6J wild-type mice. Furthermore, autophagy and autophagy-related protein 7 (ATG7) expression were decreased or increased by ERK1/2 knockdown or activation, respectively, in primary hepatocytes and liver. Blockade of autophagy by the autophagy inhibitor chloroquine or adenovirus-mediated ATG7 knockdown reversed the ameliorated liver steatosis in recombinant adenoviruses construct expressing rat constitutively active MEK1 Ad-CA MEK1 db/db mice, decreased expression of genes related to fatty acid β-oxidation and TG export, and decreased serum 3-HB levels. Finally, ERK1/2 regulated ATG7 expression in a p38-dependent pathway. Taken together, these results identify a novel beneficial role for ERK1/2 in liver steatosis via promoting ATG7-dependent autophagy, which provides new insights into the mechanisms underlying liver steatosis and important hints for targeting ERK1/2 in treating liver steatosis.

The gut-brain axis is of great importance in the control of energy homeostasis. The identification of uroguanylin (UGN), a peptide released in the intestines that is regulated by nutritional status and anorectic actions, as the endogenous ligand for the guanylyl cyclase 2C receptor has revealed a new system in the regulation of energy balance. We show that chronic central infusion of UGN reduces weight gain and adiposity in diet-induced obese mice. These effects were independent of food intake and involved specific efferent autonomic pathways. On one hand, brain UGN induces brown adipose tissue thermogenesis, as well as browning and lipid mobilization in white adipose tissue through stimulation of the sympathetic nervous system. On the other hand, brain UGN augments fecal output through the vagus nerve. These findings are of relevance as they suggest that the beneficial metabolic actions of UGN through the sympathetic nervous system do not involve nondesirable gastrointestinal adverse effects, such as diarrhea. The present work provides mechanistic insights into how UGN influences energy homeostasis and suggests that UGN action in the brain represents a feasible pharmacological target in the treatment of obesity.

Extensive research has identified enterovirus (EV) infections as key environmental triggers of type 1 diabetes. However, the underlying molecular mechanisms via which EVs contribute to the pathogenesis of type 1 diabetes remain unclear. Given that EVs dysregulate host microRNAs (miRNAs), which function as key regulators of β-cell biology, we investigated the impact of coxsackievirus B5 (CVB5) infection on the cellular expression of miRNAs within human islets. Using high-throughput quantitative PCR nanofluidics arrays, the expression of 754 miRNAs was examined in CVB5-infected human pancreatic islets. In total, 33 miRNAs were significantly dysregulated (≥ threefold difference) in the infected compared with control islets (P < 0.05). Subsequently, these differentially expressed miRNAs were predicted to target mRNAs of 57 known type 1 diabetes risk genes that collectively mediate various biological processes, including the regulation of cell proliferation, cytokine production, the innate immune response, and apoptosis. In conclusion, we report the first global miRNA expression profiling of CVB5-infected human pancreatic islets. We propose that EVs disrupt the miRNA-directed suppression of proinflammatory factors within β-cells, thereby resulting in an exacerbated antiviral immune response that promotes β-cell destruction and eventual type 1 diabetes.

Heart disease remains a major complication of diabetes, and the identification of new therapeutic targets is essential. This study investigates the role of the protein kinase MK2, a p38 mitogen-activated protein kinase downstream target, in the development of diabetes-induced cardiomyopathy. Diabetes was induced in control (MK2(+/+)) and MK2-null (MK2(-/-)) mice using repeated injections of a low dose of streptozotocin (STZ). This protocol generated in MK2(+/+) mice a model of diabetes characterized by a 50% decrease in plasma insulin, hyperglycemia, and insulin resistance (IR), as well as major contractile dysfunction, which was associated with alterations in proteins involved in calcium handling. While MK2(-/-)-STZ mice remained hyperglycemic, they showed improved IR and none of the cardiac functional or molecular alterations. Further analyses highlighted marked lipid perturbations in MK2(+/+)-STZ mice, which encompass increased 1) circulating levels of free fatty acid, ketone bodies, and long-chain acylcarnitines and 2) cardiac triglyceride accumulation and ex vivo palmitate β-oxidation. MK2(-/-)-STZ mice were also protected against all these diabetes-induced lipid alterations. Our results demonstrate the benefits of MK2 deletion on diabetes-induced cardiac molecular and lipid metabolic changes, as well as contractile dysfunction. As a result, MK2 represents a new potential therapeutic target to prevent diabetes-induced cardiac dysfunction.

At the CDKN2A/B locus, three independent signals for type 2 diabetes risk are located in a noncoding region near CDKN2A. The disease-associated alleles have been implicated in reduced β-cell function, but the underlying mechanism remains elusive. In mice, β-cell-specific loss of Cdkn2a causes hyperplasia, while overexpression leads to diabetes, highlighting CDKN2A as a candidate effector transcript. Rare CDKN2A loss-of-function mutations are a cause of familial melanoma and offer the opportunity to determine the impact of CDKN2A haploinsufficiency on glucose homeostasis in humans. To test the hypothesis that such individuals have improved β-cell function, we performed oral and intravenous glucose tolerance tests on mutation carriers and matched control subjects. Compared with control subjects, carriers displayed increased insulin secretion, impaired insulin sensitivity, and reduced hepatic insulin clearance. These results are consistent with a model whereby CDKN2A loss affects a range of different tissues, including pancreatic β-cells and liver. To test for direct effects of CDKN2A-loss on β-cell function, we performed knockdown in a human β-cell line, EndoC-bH1. This revealed increased insulin secretion independent of proliferation. Overall, we demonstrated that CDKN2A is an important regulator of glucose homeostasis in humans, thus supporting its candidacy as an effector transcript for type 2 diabetes-associated alleles in the region.

Our objective was to evaluate the relationship of urine metals including barium, cadmium, cobalt, cesium, molybdenum, lead, antimony, thallium, tungsten, and uranium with diabetes prevalence. Data were from a cross-sectional study of 9,447 participants of the 1999-2010 National Health and Nutrition Examination Survey, a representative sample of the U.S. civilian noninstitutionalized population. Metals were measured in a spot urine sample, and diabetes status was determined based on a previous diagnosis or an A1C ≥6.5% (48 mmol/mol). After multivariable adjustment, the odds ratios of diabetes associated with the highest quartile of metal, compared with the lowest quartile, were 0.86 (95% CI 0.66-1.12) for barium (Ptrend = 0.13), 0.74 (0.51-1.09) for cadmium (Ptrend = 0.35), 1.21 (0.85-1.72) for cobalt (Ptrend = 0.59), 1.31 (0.90-1.91) for cesium (Ptrend = 0.29), 1.76 (1.24-2.50) for molybdenum (Ptrend = 0.01), 0.79 (0.56-1.13) for lead (Ptrend = 0.10), 1.72 (1.27-2.33) for antimony (Ptrend < 0.01), 0.76 (0.51-1.13) for thallium (Ptrend = 0.13), 2.18 (1.51-3.15) for tungsten (Ptrend < 0.01), and 1.46 (1.09-1.96) for uranium (Ptrend = 0.02). Higher quartiles of barium, molybdenum, and antimony were associated with greater HOMA of insulin resistance after adjustment. Molybdenum, antimony, tungsten, and uranium were positively associated with diabetes, even at the relatively low levels seen in the U.S.